Keep it simple stupid.

TPN Osmolarity Calculator

To use the TPN osmolarity calculator:

  1. Select the base solutions.
  2. Enter the volume of each base solution.
  3. Click the Calculate button to determine the total base volume.
  4. Enter the amount of each additive per Bag. Please note the units of measure.
  5. Click the Calculate button to determine the final osmolarity.
  6. To start over again, click the Clear button.

Base solution
Amino acid ml
Dextrose ml
Lipid ml
Sterile Water   ml
Total volume ml
Additives (per Bag)
Ca Cl mEq
Ca Gluconate mEq
K Cl mEq
K Acetate mEq
K Phosphate mMol
Mg Sulfate mEq
Na Cl mEq
Na Acetate mEq
Na Phosphate mMol
Adult MVI-12# ml
MTE-4# ml
Osmolarity mOsmol / L
#In a central TPN the contribution of MVI and MTE to the total mOsmol is minimal, therefore they are usually excluded in the calculation. With a peripheral PN solution, these components become more important.

Calcium Phosphate Solubility Curves for Travasol

Click the button below to create a calcium phosphate solubility curve, based on the values entered above, for Travasol brand amino acid.

(solubility curve will appear in new window)

Refer to the following example of a calcium phosphate solubility curve generated by this web site.

  • Solubility curves are specific for each brand of amino acid.
  • The three curves refer to the final concentration of amino acid tested (refer to the legend).
  • The red cross denotes the intersection of Calcium (mEq/L) and Phosphate (mMol/L) concentrations in the TPN solution being evaluated.
  • If the red cross falls to the right of the appropriate curve, then CaPhos precipitation is likely to occur.
  • In the following example, one would not expect CaPhos to precipitate out of solution.
  • However there are many factors other than calcium and phosphate concentrations which influence CaPhos solubility in TPN solutions:
    • amino acid product formulation
    • amino acid concentration
    • admixture final pH
    • storage temperature
    • mixing sequence
    • dextrose concentration
    • calcium salt form
  • Because multiple factors influence solubility, the use of inline filtration is required to prevent unrecognized precipitates from reaching the patient.
  • For TNA (3-in-1) formulations the suggested upper limits are 8.5mEq calcium and 20mMol phosphorous per liter.

Ca + Phos solubility curve for Travasol

For more detailed information on calcium and phosphate solubility:
Lawrence A. Trissel. (2001). Calcium and Phosphate Compatibility in Parentereal Nutrition. Houston, TX: TriPharma Communications.
(out of print).

IV Solution Osmolarity Calculator

Alternate method

I gave my TPN osmolarity calculator idea and code to Dave at GlobalRPh, he changed it around a bit. If you compound your TPN base using grams, his calculator may be more useful:

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